A method for the two dimensional display for restriction fragments of mammalian genomic DNA has been developed. The new procedure is more rapid, less cumbersome and far more reliable than previously described procedures. The approach was used in a study of the organization and distribution of repeated sequences in the mouse genome. The linkage relationships of these elements (the members of the Bam H1 superfamily of repeated sequences) were also determined. This approach has important applications in gene mapping and for the development of a new generation of restriction fragment polymorphism probes for genetic diseases.